The current trends in the electronic industry are moving toward the fabrication of light-weight, small, fast, multi-functional, high-performance products at an economical price. Further, integrated circuits may be provided as a three-dimensional structure such as multi-chip stacked package to enhance the performance of the integrated circuit. For example, an integrated circuit having a three-dimensional structure in which a plurality of memory chips are stacked can include many signal buses for transmitting and receiving signals.